Boyer diss 2009 1046..
Boyer diss 2009 1046.. Boyer diss 2009 1046..
similarly present in the euprimate Indri (Fig. 2.37), this could also explain the “bilaminar” appearance of its medial process. Given the similarity between the medial tympanic processes of paromomyids, Indri, and plesiadapids, the more detailed interpretation of paromomyids can be applied to plesiadapids as well. Thus the apparent sutures relating to the medial tympanic process of some of the Pronothodectes specimens and the Pellouin skull likely were formed in a way similar to those of the Ignacius and Acidomomys specimens. That is, these sutures are likely to be so-called “petroso-petrosal” sutures that have been observed in Tarsius (MacPhee and Cartmill, 1986). It is explained that these sutures occur as a result of relatively rapid growth of the tympanic processes of the petrosal. SUMMARY AND CONCLUSIONS Description and analysis of new plesiadapid cranial specimens revealed the Plesiadapidae to be more diverse than previously recognized. Some features thought to be autapomorphic for the clade are revealed to be less developed in species other than P. tricuspidens. Specifically, the nasal bones are broader, the premaxillae are narrower and the external auditory meati are shorter in non-P. tricuspidens plesiadapids. Furthermore, previous conceptions of the clade’s basicranial anatomy were revised. Contrary to some previous interpretations, there is strong morphological evidence that plesiadapids have a posterolaterally positioned posterior carotid foramen; a consistent intratympanic route for the internal carotid plexus; a combined superior orbital fissure and foramen rotundum (i.e., a sphenorbital fissure); and a petrosally derived auditory bulla. These new 82
observations and interpretations may bear on previously proposed phylogenetic relationships among plesiadapids, other plesiadapiforms and euprimates. ACKNOWLEDGMENTS I am particularly grateful to R. C. Fox and C. S. Scott for allowing me to lead the description and analysis of the UALVP Pronothodectes gaoi specimens. A. Walker and T. Ryan provided HRxCT scans of this specimen and others at the Center for Quantitative Imaging, Pennsylvania State University. M. Colbert and T. Rowe provided HRxCT scans of USNM 309902 at the High-Resolution X-ray CT Facility of the University of Texas at Austin. S. Judex and C. Rubin provided HRxCT scans at the Center for Biotechnology of the Department of Biomedical Engineering at Stony Brook University. M. Godinot, P. Tassy, and C. Sagne of MNHN, and M. Pellouin provided access to important comparative specimens of Plesiadapis tricuspidens. R. Emry of the USNM granted access to and study of USNM 309902, Nannodectes intermedius. M. Jin of the AMNH granted access to and study of AMNH 17388, Nannodectes gidleyi. M. Coleman provided measurements of cochlea length in Table 2.3. J. Scott of the University of Alberta, Department of Biological Sciences helped acquire scanning electron microscope images of UALVP 46685, 46687, and 49105. J. Wible of the Carnegie Museum of Natural History assisted in interpreting soft anatomical correlates of the osteology of the tympanic region. This research was further enhanced by discussions with J. Bloch, P. Gingerich, M. Godinot, J. Perry, M. Silcox, and many other researchers. D. Krause, M. O’Leary, J. Fleagle, W. Jungers, and P. Gingerich read and enhanced 83
- Page 59 and 60: whitening, dark and light areas on
- Page 61 and 62: SYSTEMATIC PALEONTOLOGY Class MAMMA
- Page 63 and 64: efore meeting a large, anteroposter
- Page 65 and 66: The canine is a simple, single-root
- Page 67 and 68: existence and/or nature of contacts
- Page 69 and 70: outlined. This includes description
- Page 71 and 72: eneath it while also extending post
- Page 73 and 74: y a pair of parallel grooves (Fig.
- Page 75 and 76: the skull (Fig. 2.1). The length of
- Page 77 and 78: margin clearly had a posteriorly pr
- Page 79 and 80: groove measures about 0.29 mm in di
- Page 81 and 82: 2.13: 50). The suture with the supr
- Page 83 and 84: preserved (Fig. 2.15: 55). In fact,
- Page 85 and 86: the posterior septum, a deeply inci
- Page 87 and 88: Plesiadapis tricuspidens MNHN CR 12
- Page 89 and 90: is roughly 2.8 mm long. Medial to t
- Page 91 and 92: is not convoluted like many other s
- Page 93 and 94: 110) and the only squamosal/alisphe
- Page 95 and 96: two regions for the internal jugula
- Page 97 and 98: ventral to the sinuous suture (132)
- Page 99 and 100: provides measurements of these and
- Page 101 and 102: of the promontorium of the Pellouin
- Page 103 and 104: seen on the HRxCT scan is expressed
- Page 105 and 106: primates, as well as treeshrews and
- Page 107 and 108: canaliculus are present on the sept
- Page 109: it is missing from the other side o
- Page 113 and 114: REFERENCES Beard, K.C., 1993. Phylo
- Page 115 and 116: Russell, D.E., 1959. Le crâne de P
- Page 117 and 118: TABLES Table 2.1. Numerical list of
- Page 119 and 120: 81 - Occipital/petrosal suture (Fig
- Page 121 and 122: Table 2.2. Abbreviations for crania
- Page 123 and 124: Table 2.3a. Petrosal features of pl
- Page 125 and 126: Table 2.4. List of cranial measurem
- Page 127 and 128: Shape variables (Table 2.6) ac/GM -
- Page 129 and 130: Table 2.5. continued Specimen MNHN
- Page 131 and 132: Appendix Table 2.1. Specimens scann
- Page 133 and 134: Fig. 2.39 - bs, Ptr, rtp, s1, s2 Fi
- Page 135 and 136: Figure 2.1. UALVP 46685 Pronothodec
- Page 137 and 138: Figure 2.2. UALVP 46685 Pronothodec
- Page 139 and 140: Figure 2.3. UALVP 46685 Pronothodec
- Page 141 and 142: Figure 2.4. UALVP 46685 Pronothodec
- Page 143 and 144: Figure 2.5. UALVP 46685 Pronothodec
- Page 145 and 146: Figure 2.6. UALVP 49105 Pronothodec
- Page 147 and 148: Figure 2.7. UALVP 46687 Pronothodec
- Page 149 and 150: Figure 2.8. USNM 309902 Nannodectes
- Page 151 and 152: Figure 2.9. USNM 309902 Nannodectes
- Page 153 and 154: Figure 2.10. USNM 309902 Nannodecte
- Page 155 and 156: Figure 2.11. USNM 309902 Nannodecte
- Page 157 and 158: Figure 2.13. USNM 309902 Nannodecte
- Page 159 and 160: Figure 2.15. AMNH 17388 Nannodectes
similarly present in the euprimate Indri (Fig. 2.37), this could also explain the<br />
“bilaminar” appearance of its medial process.<br />
Given the similarity between the medial tympanic processes of paromomyids,<br />
Indri, and plesiadapids, the more detailed interpretation of paromomyids can be applied<br />
to plesiadapids as well. Thus the apparent sutures relating to the medial tympanic<br />
process of some of the Pronothodectes specimens and the Pellouin skull likely were<br />
formed in a way similar to those of the Ignacius and Acidomomys specimens. That is,<br />
these sutures are likely to be so-called “petroso-petrosal” sutures that have been observed<br />
in Tarsius (MacPhee and Cartmill, 1986). It is explained that these sutures occur as a<br />
result of relatively rapid growth of the tympanic processes of the petrosal.<br />
SUMMARY AND CONCLUSIONS<br />
Description and analysis of new plesiadapid cranial specimens revealed the<br />
Plesiadapidae to be more diverse than previously recognized. Some features thought to<br />
be autapomorphic for the clade are revealed to be less developed in species other than P.<br />
tricuspidens. Specifically, the nasal bones are broader, the premaxillae are narrower and<br />
the external auditory meati are shorter in non-P. tricuspidens plesiadapids. Furthermore,<br />
previous conceptions of the clade’s basicranial anatomy were revised. Contrary to some<br />
previous interpretations, there is strong morphological evidence that plesiadapids have a<br />
posterolaterally positioned posterior carotid foramen; a consistent intratympanic route for<br />
the internal carotid plexus; a combined superior orbital fissure and foramen rotundum<br />
(i.e., a sphenorbital fissure); and a petrosally derived auditory bulla. These new<br />
82
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